Continued development of lithium-ion batteries is limited by the shortage of Li element. In this situation, the exploration of high-performance sodium-ion batteries is attracting much attention. In this experimental work, Na2/3Ni1/4Mn34O2 film cathode materials were fabricated by excimer laser deposition at different oxygen partial pressures. X-ray diffraction studies and field emission scanning electron microscopy revealed high c-axis orientation and uniform grain distribution, respectively, in the deposited films. Furthermore, after 30 cycles under a current density of 13 mA g−1, the film samples deposited at an oxygen partial pressure of 65 Pa exhibited a high capacity-retention of 91%. The film structure also had a large-current discharge performance, which makes practical applications possible.

Molecular crystals are complex systems exhibiting various crystal structures, and accurately modeling the crystal structures are essential for understanding their physical behaviors under high pressure. Here, we have performed an extensive structure searches of ternary carbon-nitrogen-oxygen (CNO) compound under high pressure by CALYPSO method and first principles calculations and successfully identified three polymeric CNO compounds with $ Pbam $,$ C2/m $ and $ I\bar{4}m2 $ symmetries under 100 GPa. Most interestingly, these structures are also dynamically stable at ambient pressure, and are potential high energy density materials (HEDMs). The energy densities of $ Pbam $, $ C2/m $ and $ I\bar{4}m2 $ phases of CNO are about 2.30 kJ/g, 1.37 kJ/g and 2.70 kJ/g, respectively, with the decompositions of graphitic carbon and molecular carbon dioxide and $\alpha$-N (molecular $ \rm N_2 $) at ambient pressure. The present results offer in-depth insights into the structural evolution and physical properties of CNO compounds under high pressures, which offer crucial insights for the design and synthesis of novel HEDMs.

In this experiment, the stable output of a dual-frequency laser source is obtained by an acousto-optic modulator due to the Bragg diffraction effect. Furthermore, the non-polarized dual-laser heterodyne interferometer is designed to measure the micro-movement of stacked piezoelectric (PZT) ceramic. This micro-movement can be dynamically determined by comparing the phase difference between the conference beam and measuring beam. The results indicate that the micro-movement of PZT ceramic changes linearly with the driven-voltage in the range of 0–30 V and the sensitivity of movement to voltage is 58.3 nm/V, which is very close to the theoretical value and this laser heterodyne interferometer can be applied for calibrating parameters of PZT ceramic.